Are you sure it's 2 triangles or one? It would be helpful if you could post your vector drawing on the board.
If it's one triangle then you can apply the Pythagoras theorem and get the answer pretty easily. The plane would be moving east and the wind would be acting at right angles from the north. It forms a right-angled triangle.
From there you can find the resultant vector.
With the wind acting, the plane wouldn't be flying straight east but as a resultant. Then you can find the angle, which should be its deviation from the path due east.
I might be wrong; if you could post your diagram it'd be a big help. :)